code: def create_critic_network(
      obs_fc_layer_units, action_fc_layer_units, joint_fc_layer_units
  ):
      """Create a critic network for DDPG."""
  
      def split_inputs(inputs):
          return {"observation": inputs[0], "action": inputs[1]}
  
      obs_network = (
          create_fc_network(obs_fc_layer_units)
          if obs_fc_layer_units
          else create_identity_layer()
      )
      action_network = (
          create_fc_network(action_fc_layer_units)
          if action_fc_layer_units
          else create_identity_layer()
      )
      joint_network = (
          create_fc_network(joint_fc_layer_units)
          if joint_fc_layer_units
          else create_identity_layer()
      )
      value_fc_layer = tf.keras.layers.Dense(
          1,
          activation=None,
          kernel_initializer=tf.keras.initializers.RandomUniform(
              minval=-0.003, maxval=0.003
          ),
      )
  
      return sequential.Sequential(
          [
              tf.keras.layers.Lambda(split_inputs),
              nest_map.NestMap(
                  {"observation": obs_network, "action": action_network}
              ),
              nest_map.NestFlatten(),
              tf.keras.layers.Concatenate(),
              joint_network,
              value_fc_layer,
              inner_reshape.InnerReshape([1], []),
          ]
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import functools
  import os
  import time
  from absl import app
  from absl import flags
  from absl import logging
  import gin
  from six.moves import range
  import tensorflow
  from tf_agents.agents.ddpg import ddpg_agent
  from tf_agents.drivers import dynamic_step_driver
  from tf_agents.environments import parallel_py_environment
  from tf_agents.environments import suite_mujoco
  from tf_agents.environments import tf_py_environment
  from tf_agents.eval import metric_utils
  from tf_agents.keras_layers import inner_reshape
  from tf_agents.metrics import tf_metrics
  from tf_agents.networks import nest_map
  from tf_agents.networks import sequential
  from tf_agents.replay_buffers import tf_uniform_replay_buffer
  from tf_agents.utils import common
label_desc: Use image node_id 5 for calling a global function with example usage: create_critic_network(obs_fc_layer_units, action_fc_layer_units, joint_fc_layer_units) and returns: sequential, dict